Oxidation behaviors of carbon fiber reinforced multilayer SiC-Si3N4 matrix composites

Abstract

Oxidation behaviors of carbon fiber reinforced SiC matrix composites (C/SiC) are one of the most noteworthy properties. For C/SiC, the oxidation behavior was controlled by matrix microcracks caused by the mismatch of coefficients of thermal expansion (CTEs) and elastic modulus between carbon fiber and SiC matrix. In order to improve the oxidation resistance, multilayer SiC-Si3N4 matrices were fabricated by chemical vapor infiltration (CVI) to alleviate the above two kinds of mismatch and change the local stress distribution. For the oxidation of C/SiC with multilayer matrices, matrix microcracks would be deflected at the transition layer between different layers of multilayer SiC-Si3N4 matrix to lengthen the oxygen diffusion channels, thereby improving the oxidation resistance of C/SiC, especially at 800 and 1000 °C. The strength retention ratio was increased from 61.9% (C/SiC-SiC/SiC) to 75.7% (C/SiC-Si3N4/SiC/SiC) and 67.8% (C/SiC-SiC/Si3N4/SiC) after oxidation at 800 °C for 10 h.

Effects of Al 2 O 3 –Y 2 O 3 /Yb 2 O 3 additives on microstructures and mechanical properties of silicon nitride ceramics prepared by hot‐pressing sintering

“…Fewer elongated grains are observed in specimen SN‐AY than in specimen SN‐AYb, which is the reason for its relatively low strength. In other words, elongated β‐Si 3 N 4 grains reinforce Si 3 N 4 ceramics similar to other whisker‐reinforced materials 36,37 . Moreover, the research shows that when the ceramic is close to complete compactness, the grain refinement can improve the flexural strength.…”

“…In other words, elongated β-Si 3 N 4 grains reinforce Si 3 N 4 ceramics similar to other whisker-reinforced materials. 36,37 Moreover, the research shows that when the ceramic is close to complete compactness, the grain refinement can improve the flexural strength. This can be understood through the well-known Hall-Petch relationship.…”

Formation mechanism and roles of oxygen vacancies in melt-grown Al2O3/GdAlO3/ZrO2 eutectic ceramic by laser 3D printing

“…For example, the microstructures of the directionally solidified Al 2 O 3 /Y 3 Al 5 O 12 and Al 2 O 3 /GdAlO 3 eutectic composites nearly maintain unchanged even after annealed at 1700 for 1000 h, and their flexural strengths are ℃ almost constant during the annealing process [2,3]. Besides, oxide ceramic possesses unpaired oxidation resistance, as compared with other ceramics such as SiC [6][7][8][9]. As a result, these exciting performances make the oxide eutectic composite one of the most promising candidates for new generation of hightemperature structural materials applied in the fields of aerospace and power generation system.…”

Effect of La2O3 content on the oxygen barrier ability of the HfB2‐SiC coating at 1973 K

“…Carbon materials are appealing lightweight, high‐strength thermal structural materials used in aerospace equipment components due to their low density, outstanding high‐temperature strength, low coefficient of thermal expansion (CTE), and superior heat shock resistance 1–7 . Nevertheless, the high oxygen sensitivity of carbon materials renders them vulnerable to catastrophic oxidation at high temperatures and aerobic settings over 723 K, resulting in weight loss by gasification, 8,9 which significantly accelerates their structural degradation.…”

“…Carbon materials are appealing lightweight, high-strength thermal structural materials used in aerospace equipment components due to their low density, outstanding hightemperature strength, low coefficient of thermal expansion (CTE), and superior heat shock resistance. [1][2][3][4][5][6][7] Nevertheless, the high oxygen sensitivity of carbon materials renders them vulnerable to catastrophic oxidation at high tem-# Deyu Qian, Yuexing Chen, and Xuanru Ren contributed equally to this work and should be considered co-first authors peratures and aerobic settings over 723 K, resulting in weight loss by gasification, 8,9 which significantly accelerates their structural degradation. The applied protective coating technique can form a diffusion barrier between the carbon material and oxygen, which has proven to be an effective method for improving the high-temperature stability of the carbon materials.…”